chapter 16

• Immune system


  Specific host defense mechanism and the third line of defense
• Immunology


  The scientific study of the immune system and responses
• Immunologists


  Scientists who study various aspects of the immune system
• Immunologists are research scientists or practicing specialists who study, analyze, or treat disease processes that involve the immune system
• To become an immunologist, one must have, in addition to a PhD or an MD, at least 2 to 3 years of training in an accredited program and must pass an examination given by the American Board of Allergy and Immunology
• Many immunologists are employed in research, where new findings and treatments are discovered for persistent illnesses, such as allergies, pneumonia, and abscesses
• Pediatric immunologists (also known as pediatric allergists) specialize in children and typically work in children's hospitals, community hospitals, private offices, and university medical centers
• Pediatric immunologists possess a medical degree and additional years of training in specialized immunology/allergy programs
• Immune system


  The third line of defense, a specific host defense mechanism that springs into action to defend against a specific pathogen (or other foreign object) that has gained entrance to the body
• Edward Jenner's smallpox vaccine first administered


  1796
• Louis Pasteur develops vaccines against anthrax, cholera, and rabies


  Late 1800s
• Pasteur first used the terms immune and immunity
• Jenner and Pasteur did not understand how or why their vaccines worked
• Emil Behring and Kitasato Shibasaburo discover antibodies while developing a diphtheria antitoxin


  1890
• Elie Metchnikoff discovered phagocytes and introduced the cellular theory of immunity
• By 1910, the main elements of clinical immunology (i.e., allergy, autoimmunity, and transplantation immunity) had been described, and immunochemistry had become a quantitative science
• Major advances in immunology began to take shape in the late 1950s, when the focus shifted from serology (investigating antigens and antibodies in serum) to cells
• Defining the role of lymphocytes signaled the start of the new era in immunology
• The emphasis on immune cells and the emergence of the concepts and tools of molecular biology were the two most powerful influences on immunology since its inception
• The roots of medical laboratory immunology are found in clinical microbiology-the very first immunologic procedures were designed to diagnose infectious diseases
• In some medical facilities (primarily small ones), immunologic procedures are still performed in microbiology laboratories
• In larger hospitals and medical centers, immunologic procedures are performed in an Immunology Laboratory, which is separate from the Clinical Microbiology Laboratory (CML)
• Antigens


  Molecules (usually proteins) that stimulate the immune system to produce antibodies
• Antibodies


  Protein molecules that a person's immune system produces in response to antigens
• Primary functions of the immune system


  • Differentiate between "self" and "nonself" (something foreign)
  • Destroy that which is nonself
• Two major arms of the immune system


  • Humoral immunity
  • Cell-mediated immunity (CMI)
• Humoral immunity


  Always involves the production of antibodies, with antibodies playing a major role
• Cell-mediated immunity (CMI)


  Involves many different cell types, with antibodies playing only a minor role, if any
• Antibody-mediated immunity (AMI)


  Another term for humoral immunity, since it is mediated by antibodies
• Humans are immune to certain infectious diseases simply because they are humans, as human cells do not possess the appropriate cell surface receptors for some pathogens that cause diseases of pets
• Acquired immunity


  Immunity that results from the active production or receipt of protective antibodies during one's lifetime
• Types of acquired immunity


  • Active acquired immunity
  • Passive acquired immunity
• Active acquired immunity


  Immunity that results from the active production of protective antibodies within the person's body, usually long-lasting
• Passive acquired immunity


  Immunity that results from the person receiving antibodies that were produced by another person or animal, usually only temporary
• Categories of acquired immunity


  • Natural (or naturally occurring) active acquired immunity
  • Artificial (or artificially occurring) active acquired immunity
  • Natural passive acquired immunity
  • Artificial passive acquired immunity
• Active acquired immunity


  Immunity that results from the active production or receipt of protective antibodies during one's lifetime
• Types of active acquired immunity


  • Natural (or naturally occurring) active acquired immunity
  • Artificial (or artificially occurring) active acquired immunity
• Natural active acquired immunity


  Immunity that is acquired in response to the entry of a live pathogen into the body (i.e., in response to an actual infection)
• Artificial active acquired immunity


  Immunity that is acquired in response to vaccines
• Types of passive acquired immunity


  • Natural passive acquired immunity
  • Artificial passive acquired immunity